Table 1 Description of the variables included in the final dataset

Attributor code (initials, date of birth, sex and D[A]AT of residence)

Used to identify an individual

Sex

Female or male

Age at triage

Categorised into 18–24, 25–34, 35–44, 45–54 and 55–74

Date of triage and discharge

Used to identify the start and end of each episode of treatment

Outcome code

Retained, dropped out or other (see results section for other outcomes)

Ethnicity code

White (white British, white Irish, white other)

Mixed (white and black Caribbean, white and black African, white and Asian, other mixed)

Asian/Asian British (Indian, Pakistani, Bangladeshi, other Asian)

Black/Black British (Caribbean, African, other black)

Other (Chinese, other)

D(A)AT of residence

Recoded to public health zone of residence

Cheshire and Merseyside (Cheshire, Halton, Knowsley, Liverpool, Sefton, St Helens, Warrington, Wirral)

Cumbria and Lancashire (Blackburn, Blackpool, Cumbria, Lancashire)

Greater Manchester (Bolton, Bury, Manchester, Oldham, Rochdale, Salford, Stockport, Tameside, Trafford, Wigan)

Referral source

Recoded to criminal justice and non-criminal justice referral route

Non-criminal justice referral route (Accident and Emergency departments, Community Care Assessment, Connexions, drug service: non-statutory, drug service: statutory, Education Services, Employment Services, General Practitioner, looked after children, Psychiatry, self, Social Services, needle exchange services)

Criminal justice referral route (Arrest Referral/Drug Interventions Programme, CARAT, Drug Treatment and Testing Order, Probation, Youth Offending Team)

Recent treatment contact

No (no treatment contact in 2003/04 or 2004/05) or yes (treatment contact in 2003/04 or 2004/05)

Opiate use

No or yes (heroin, methadone, other opiates)

Stimulant use

No or yes (amphetamine, cocaine, crack cocaine)

Alcohol use

No or yes

Deprivation

Assessed using a composite score: the Index of Multiple Deprivation. The index is based on data for seven domains: income, employment, health and disability, education, skills and training, barriers to housing and services, living environment and crime. A higher score reflects a higher level of deprivation. Table 2 shows the scores for each D(A)AT area and the quintiles used for the analyses.